This invention relates to solving leakage problems in toner hoppers used in Xerography and more specifically in the toner cartridge remanufacturing industry. This includes copiers, laser printers and facsimile machines.
CANON has designed an all-in-one cartridge as in U.S. Pat. No. 4,975,744, issued Dec 4, 1990 and assigned to CANON. Several companies have used these cartridges in laser printers, copy machines and facsimile machines, each with the varying printer engines and a different nameplate. Originally, these cartridges were designed to be "disposable". However, after the first all-in-one toner cartridge was introduced, it did not take long before laser cartridge remanufacturers such as myself began remanufacturing cartridges. These "disposable" cartridges were designed to function for only one cartridge cycle without remanufacturing. The remanufacturers had found certain components that needed replacement on a regular basis. In 1990, the first aftermarket photoreceptor drum became available for use in remanufacturing the all-in-one cartridge of the "SX" engine variety, the most popular printer cartridge from around 1987 through 1994 at the time of this writing. When the long-life photoreceptor drum became available, the entire remanufacturing industry turned around and gained great strength and began a huge growth surge that still continues. In October 1993, HEWLETT-PACKARD, the largest seller of this printer engine using the all-in-one cartridge, entered the cartridge remanufacturing industry with the "Optiva" cartridge, further increasing the size as well as credibility of this relatively new industry. However, this relatively new industry grew from the all-in-one cartridge shortly after its debut. Before the introduction of the long-life drum, sometimes called the "superdrum" or "duradrum" the SX cartridge would last for around three cartridge remanufacturing cycles at best, since the maximum useful life of the OEM drum was three cycles. However, the long-life drums got their names from the fact that they were designed to last for many remanufacturing cycles or recharges as they are sometimes called. Typically, the long life drum can last for ten or more such cycles, unlike the typical OEM(Original Equipment Manufacturer) drum. With the additional developments of drum coatings, originally designed for OEM drums, the long-life drum may last for many additional cycles. Some coatings, in theory, were designed to be dissolved and removed from over the drum surface every 1-3 cycles, so the drum life of the long-life drum almost seems limitless.
However, with photoreceptor drums lasting for many cycles, other components of the cartridge have a tendency to require greater durability, a better solution, or a greater life. Also, as the success of these cartridges has skyrocketed, the demand is for cartrides with longer cycles, so component improvements are significant. Therefore, avoiding natural problems with prevention means must also be implemented for cartridges of longer life both in longer cycle times and greater number of cycles.
In 1992, the EX printer, otherwise known as the Series 4, and its special toner cartridge were introduced. Eventually the Series 4+ printer was introduced in 1994, using the same toner cartridge. The toner hopper of the EX Series-4/4+ toner cartridge has a time-generated flaw. After 2000 to 8000 pages are printed, a leakage tends to begin. The cartridge was designed by the manufacturer to last for only 6000 pages. Every component has a wear-life. Whether the failure was intentional or by accident on the part of the OEM manufacturer, the wear-life-related flaw occurs. It is assumed that the flaw was by accident on the part of the OEM manufacturer, and since 1992, they and the entire toner cartridge remanufacturing industry were unaware of this flaw and how to fix it.
People in the toner cartridge industry could never figure what the cause of the leakage was. Rumor in the industry was that the leakage was caused by a poor ultrasonic weld in the toner hopper, where the toner hopper is joined into 2 parts, where the heat seal is attached. According to the misinformation, the poor ultrasonic weld caused a toner leakage through the seam where the 2 portions of the toner hopper join, thus causing toner leakage. Applicants have found otherwise, have found the actual true cause of the leakage, and have, therefore been able to find a solution to the problem.
The EX series-4 toner cartridge has a white plastic bushing which is inserted through a side wall of the toner hopper for connection to a toner stir-rod inside the toner hopper. The plastic bushing is driven by the imaging machine through a reducing gearbox in the cartridge such that it rotates the stir-rod to prevent the toner from lumping and to keep the toner mixed within the hopper. The bushing has a portion which remains outside the hopper, and a felt gasket pinched between this portion and the side wall of the hopper is supposed to prevent toner from leaking out of the hopper at the location of the bushing.
Toner cartridge technicians have been trying to figure out why the cartridge leaks. Applicants have done extensive research and testing on this problem. To the best of applicants' knowledge, nobody else in the cartridge remanufacturing industry completely understands the problem or has developed a soulution.
It is harder for a gasket to seal a moving part than a stationary part. The felt gasket compresses over time and becomes permanently thinner or deformed. A need exists for an inexpensive gasket which retains its sealing properties for a long period of time and keeps the connection between the bushing and hopper tight so the bushing doesn't wobble. Furthermore, a need exists for an addition to the old used gasket to make it last a long time.
A co-inventer of this application has a U.S. Pat. No. 5,296,902, granted Mar. 22, 1994, which discloses a sealing material for replacing the felt-like seals at the ends of the feed roller on a toner cartridge assembly. The sealing material is a crush-resistant velvet (polyester) or felt attached to a foam backing. The description of that sealing material is hereby incorporated by reference into this application.